MDC1200 is a communications protocol used mainly in public safety radio communications. It was patented by Motorola, but the patent has now expired, and it is being implemented by many other vendors. While providing a very basic protocol for exchange of data, its main use is for PTT-ID, or automatic identification of the transmitting unit via a quick audio "chirp" carrying encoded data which identifies the unit. MDC1200 transmits data at 1,200 baud.
As of circa-2006, the only way to encode or decode MDC1200 was to either use Motorola hardware, or accessory adapters from a vendor such as Midians who licensed the technology from Motorola.
There was one notable project a few years back which presented supposedly-working C code to encode and decode MDC1200 PTT-ID. As I begin to search around again, I will keep this updated with the most current programming information.